A pressure sensor includes a pressure sensing element and a top cap. The pressure sensing element includes a bonded wafer substrate having a buried sealed cavity. A wall of the buried sealed cavity forms a sensing diaphragm. One or more sense elements may be supported by the sensing diaphragm and one or more bond pads are supported by the upper side of the bonded wafer substrate. Each of the bond pads may be positioned adjacent to the sensing diaphragm and electrically connected to one or more of the sense elements. The top cap may be secured to the upper side of the bonded wafer substrate such that an aperture in the top cap facilitates passage of a media in a downward direction to the sensing diaphragm. The top cap may be configured to isolate the bond pads from the media.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An absolute pressure sensor comprising: a pressure sensing element including: a bonded wafer substrate having a buried sealed cavity, wherein a wall of the buried seal cavity forms a sensing diaphragm along on an upper side of the bonded wafer substrate, wherein the bonded wafer substrate comprises a first substrate that is direct bonded to a second substrate, and wherein the buried sealed cavity is defined by a void between the first substrate and the second substrate, wherein the first substrate and the second substrate are formed from silicon; one or more sense elements supported by the sensing diaphragm of he bonded wafer substrate; one or more bond pads supported by the upper side of the bonded wafer substrate, wherein each of the one or more bond pads positioned adjacent to the sensing diaphragm and electrically connected to one or more of the one or more sense elements; a top cap including an aperture, the top cap secured relative to the upper side of the bonded wafer substrate such that the aperture facilitates passage of a media in a downward direction to the sensing diaphragm, the top cap further configured to isolate the one or more bond pads of the pressure sensing element from the media, wherein the top cap is secured to the upper side of the bonded wafer substrate via at least one of an anodic bond or a glass frit bond; and a carrier coupled to a lower side of the second substrate.
2. The absolute pressure sensor of claim 1 , wherein the buried sealed cavity is a reference pressure cavity.
3. The absolute pressure sensor of claim 1 , wherein the buried sealed cavity is defined by an enclosed and sealed void between a lower surface of the bonded wafer substrate and an upper surface of the bonded wafer substrate.
4. The absolute pressure sensor of claim 1 , wherein the buried sealed cavity is a vacuum sealed reference cavity.
5. The absolute pressure sensor of claim 1 , wherein the one or more sense elements include one or more piezoresistive elements.
6. The absolute pressure sensor of claim 1 , further comprising a pressure port in fluid communication with the aperture.
7. The absolute pressure sensor in claim 6 , wherein the pressure port and the aperture define, at least in part, a media flow path that is isolated from the one or more bond pads of the pressure sensing element.
8. The absolute pressure sensor of claim 1 , wherein the bonded wafer substrate includes a Silicon-On-Insulator (SOI) substrate.
9. The absolute pressure sensor of claim 1 , wherein the pressure of the media is measured relative to the pressure in the buried sealed cavity.
10. The absolute pressure sensor of claim 1 , wherein the top cap includes a hole or recess that is in registration with one or more of the one or more bond pads such that when the top cap is bonded relative to the upper side of the bonded wafer substrate, the one or more bond pads are accessible through the hole or recess for electrical connection.
11. The absolute pressure sensor of claim 1 , wherein the carrier comprises a ceramic carrier, a glass carrier, or a printed circuit board.
12. A pressure sensor comprising: a pressure sensing element including: a first substrate; a second substrate; the first substrate direct bonded to the second substrate such that a recess formed in the first substrate and/or second substrate creates a sealed cavity between the first substrate and the second substrate, wherein the first substrate and the second substrate comprise silicon; the first substrate defining a sensing diaphragm that forms part of the sealed cavity; one or more sense elements supported by the sensing diaphragm of the first substrate; a bond pad supported by the first substrate, wherein the bond pad is positioned adjacent to the sensing diaphragm and electrically connected to one or more of the one or more sense elements; a top cap including an aperture, the top cap is secured relative to the first substrate such that the aperture facilitates passage of a media in a downward direction to the sensing diaphragm of the first substrate, the top cap configured to isolate the bond pad of the pressure sensing element from media, wherein the top cap is secured to the upper side of the bonded wafer substrate via at least one of an anodic bond or a glass frit bond; a pressure port coupled to the top cap, the pressure port defining a fluid passage way to the aperture in the top cap; and a carrier coupled to a lower side of the second substrate.
13. The pressure sensor of claim 12 , wherein the sealed cavity is a sealed m reference cavity.
14. The pressure sensor of claim 12 , wherein the one or more sense elements include one or more piezoresistive elements formed on the sensing diaphragm of the first substrate.
15. The pressure sensor of claim 12 , further comprising signal conditioning circuitry for conditioning a signal that is responsive to the one or more sense elements.
16. The pressure sensor of claim 12 , wherein the top cap includes a hole or recess that is in registration with one or more of the one or more bond pads such that when the top cap is bonded relative to the upper side of the bonded wafer substrate, the one or more bond pads are accessible through the hole or recess for electrical connection.
17. The pressure sensor of claim 12 , wherein the bonded wafer substrate includes a Silicon-On-Insulator (SOI) substrate.
18. A method of making a pressure sensor, comprising: obtaining a bonded wafer substrate having a buried sealed cavity, wherein a wall of the buried seal cavity forms a sensing diaphragm along on an upper side of the bonded wafer substrate, wherein the bonded wafer substrate comprises a first substrate direct bonded to a second substrate, and wherein the bonded wafer substrate comprises silicon; providing one or more sense elements on the sensing diaphragm of the bonded wafer substrate; providing one or more bond pads on the upper side of the bonded wafer substrate, each of the one or more bond pads positioned adjacent to the sensing diaphragm and electrically connected to the one or more of the sense elements; securing a top cap to the upper side of the bonded wafer substrate via at least one of an anodic bond or a glass frit bond, the top cap including an aperture that facilitates passage of a media in a downward direction to the sensing diaphragm, the top cap also isolating the one or more bond pads from the media during use; and coupling a carrier to a lower side of the second substrate.
19. The method of claim 18 , wherein the one or more sense elements include one or more piezoresistive elements.
20. The method of claim 18 , wherein the top cap includes a hole or recess that is in registration with one or more of the one or more bond pads such that when the top cap is bonded relative to the upper side of the bonded wafer substrate, the one or more bond pads are accessible through the hole or recess for electrical connection.
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September 12, 2013
October 18, 2016
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